Ants rasp and chirp by scraping a spike on their waist against a ridged section of their abdomen. But developing larvae are silent. So ants recognize them by chemical cues, size, shape, even squishiness. But the teenage versions of ants—the pupae—have hard outer shells that lack pheromones.

However, pupae do have fully formed sound organs. The researchers thus recorded audio from the pupae and discovered clicking noises. The pulses' frequency and intensity are more like the adult workers' stridulations than the queen ant's song.

The pupae’s snaps are brief because their cases keep them from moving much. Still, the noise appears to work: when the researchers disturbed the nest, adult ants rescued noisy pupae before silent larvae. For ants, as for people, it pays to be the squeaky wheel.